Hosted by: Qin Wu

In this talk, I will show that a subsystem formulation of DFT can simplify both the theoretical framework and the computational effort for calculating the electronic structure of condensed phase systems. I claim that the naturally subsystem-like form of molecular aggregates (including molecules at surfaces) makes subsystem DFT a better descriptor of the underlying physics than regular DFT of the supersystem. This claim will be sustained by two examples. The first one is a novel van der Waals DFT theory based on the subsystem DFT approach which addresses several drawbacks of common vdW functionals as well as SAPT-type formulations â€" it is theoretically exact and amenable to sensible approximations. The second example involves the analysis of the electronic spectra of molecular chromophores embedded in a molecular environment. It uncovers interactions between the chromophore and its environment which we term "holographic spectrum". Computational evidence to the claims will be provided, and it is obtained from a local version of the Amsterdam Density Functional software and a brand new implementation of subsystem DFT (both ground and excited states) in the plane wave code Quantum-Espresso. I will discuss several pilot calculations which include molecules at surfaces and layered systems. Recent references from the Pavanello group: [1] On the subsystem formulation of linear-response time-dependent DFT, J. Chem. Phys. 138 , 204118 (2013) [2] Subsystem real-time Time Dependent Density Functional Theory, J. Chem. Phys. submitted, arXiv:1502.01324 [3] Periodic subsystem density-functional theory, J. Chem. Phys. 141 , 174101 (2014) [4] FDE-vdW: A van der Waals inclusive subsystem density-functional theory, J. Chem. Phys. 141 , 044127 (2014) [5] Quantifying Environmental Effects on the Decay of Hole Transfer Couplings in Biosystems, J. Chem. Theory Comput., 2014, 10 (6), pp 2546��"2556